On 2008-03-05, Joseph Gwinn wrote:
In article ,
"DoN. Nichols" wrote:
[ ... ]
Understood. When I got the lathe with the bed turret as part of
it (matching serial number) I had to get more tooling so I could use it
fully. I already had experience with various lathes from around that
size on down to tiny, but no turret experience. The turret came loaded
with three 1/2" Jacobs chucks and two floating reamer holders -- end of
list. :-)
Well, no turret in my batch. But I'm liking Aloris better and better.
You might find a turret on eBay -- I've seen them for sale from
time to time. But it won't be a matching serial number. :-) I believe
that I pointed you to a PDF scan of the manual (very faded
third-generation Xerox copy), and from that you can get several possible
part numbers -- all were interchangeable, apparently.
[ ... ]
The boring bar hole in various holders is probably pretty good, as
Aloris makes them on some kind if production line, but they make no
claim of repeatability between holders.
And if you mix manufacturers, the difference may be much
greater.
Yep.
And since some of my tooling is always purchased used, there may
have been changes in Aloris' dimensions over the years, too.
[ ... ]
Mine appears to have 0.048" of backlash, judged by turning the handle
and reading the dial drum.
O.K. Mine as a bit over 0.070" -- nearly 3/4 of a turn, and the
leadscrew was going to start wearing a lot faster.
Much worse.
Agreed. Both the leadscrew and the nut were really badly worn.
Compare the backlash in the middle of travel to that at the ends
to see how much is in the leadscrew and how much is in the nut. If you
go to the point where the leadscrew is just barely fully in the nut you
should be measuring just the wear in the nut, since the leadscrew is
very seldom used in that range. And the more difference in backlash
between the ends and the middle, the more cumulative error in the dial
reading. I got both leadscrew and nut at the same time.
It's 0.055" at one end and 0.040 at the other, and the dovetail gets
looser at one ned versus the other.
O.K. I think that you should replace the leadscrew at the same
time as the nut, then.
Most of the problem seems to be in the nut. Maybe I'll make a new nut.
It was pretty simply shaped, and an Acme tap set is probably cheaper
than a new nut from Clausing. It's $48.50.
First thing to be careful about. The thread is 1/2-10 Acme
*LH*, and all of the combination roughing/finishing Acme taps have been
right-hand only. I did get a left-hand Acme tap of the right thread,
but IIRC it cost nearly as much as the nut at that time.
What does your nut look like? Mine looks like a plumbing Tee,
with the Acme thread through the two straight sides, and the upright of
the 'T' turned for a certain length and then a shoulder left to keep the
Acme thread's centerline the right distance below the cross-slide.
There is a hole drilled through the upright, with a spring-loaded ball
oiling point in the center so you can get oil to the leadscrew and nut
easily (after sweeping off lots of chips, of course. :-) This is one
reason why I normally keep the taper attachment unmounted. The Nut
looks like an over-tall Quonset hut of bronze brazed to a 'U' of 1/4"
square steel, and it is allowed to slide back and forth when the taper
attachment sides. This means that it is more difficult to get oil to
the leadscrew and especially into the nut.
Some of these days I'll get a chunk of bronze of adequate size
and use it to make a new nut. Then I'll make a matching leadscrew so I
am ready for the next time it wears out. :-) And -- this will give me
practice in making spare leadscrews and nuts for the taper attachment
too, so if the taper attachment wears fast, I can swap back in a normal
nut and leadscrew. (Actually -- the leadscrew is identical for both
the standard cross slide and my taper attachment -- but not for the
fancier taper attachment with the telescoping leadscrew.
There may simply be small errors in the curvature turned in the
ring, and if there is any error, I would expect that the rocker should
make contact at the OD first. I wonder whether it was turned with a
form tool, or a radius turning tool.
The slot appears to have been made by plunging a form cutter held in a
horizontal mill into the stock about 0.25".
Huh? I thought that we were talking about the curvature in the
ring which surrounds the lantern toolpost. That can be slipped over the
toolpost for measuring the radius with the toolpost out of the way.
I don't see any Armstrong markings.
O.K.
The part I'm talking about above is a very thick washer (Tool Post
Washer, C-375) that fits over the toolpost, and having a shallow slot
milled into one face to accept the rocker (Tool Post Wedge, C-378). The
bottom of the slot appears to be spherical.
Interestingly, the drawing (page 30) in the Clausing 5914 manual shows a
washer with a full spherical seat on one side, versus a slot, so the
slotted washer was probably a later design. The slotted washer is
probably easier to make, and stronger.
Aha! It suddenly makes sense what you have been saying. i've
only ever seen the ones with the full spherical relief on the washer.
[ ... ]
O.K. No radius gauges in the proper size range? :-)
Not that big. Nor that narrow at the tip, to allow use at the bottom of
a narrow slot perpendicular to the slot.
Again -- slip the ring off the top of the toolpost and measure
it free standing.
Getting the ring off the toolpost isn't the problem. It's the
restricted access to the bottom of the slot.
Which I never saw.
But to my mind it would *have* to be a conical section at least
to handle the motion of the rocker.
As for a tool to measure the radius -- try three rods on a set of
three collars which can allow the rods to both pivot and to slide back
and forth to set a radius. The extension of the rods which allows the
rods to pivot throughout the range of the curve and have all three
continue touching would be set to the true radius. I've seen such a
tool in an old Machinist's toolbox.
I'm not visualizing this.
It doesn't matter, though this would still work even with your
slotted washer instead of the turned washer.
I can't really do a full ASCII drawing, but pictu
_
| |
||||||||||||||| --- knurled nut
+-------+
| |
| 0 |1
| |
+-------+
+-------+
| |
| 0 |2
| |
+-------+
+-------+
| |
| 0 |3
| |
+-------+
||||||||||||||| --- knurled nut
|_|
a) Now -- part (2) there has a threaded shaft projecting from each
end through (1) and (3)
b) The holes, (shown as '0' in each part) are off center enough to
clear the threaded shafts passing through parts (1) and (3).
c) Not shown -- small thumbscrews to lock shafts into the holes.
Loosen them and the shafts slide, tighten them and the shafts
are locked in place.
d) The shaft in (2) is straight, coming to a point.
e) The shafts in (1) and (3) are straight except at the end where
they are bent in to almost touch the tip of the shaft in (2).
f) If you adjust the shafts so the tips are the same distance from
the centerline of the assembly above, then loosen the knurled
nuts and pivot each to they are forming something like "|",
all three points will touch on a curve of a radius which matches
the distance of the tips from the centerline. If the radius is
larger or smaller, only two of the tips will touch.
g) So -- the trick is how to measure the radius of the tip from the
center. For that, you will have to design and make your own
fixture. I've "designed" the tool. :-)
h) Note that the holes in (b) above *could* be on center if the
studs are large enough to accept a through hole with a
countersink bevel on each side -- though this would limit the
swiveling of the rods to something like +/- 45 degrees or so.
[ ... ]
I think that the cylinder is intentional for sure - the cylinder is
cheaper to make. With a section of a sphere, clamping is firm and
distributed over a broad area even if the bar being clamped isn't quite
rectangular. Which is why Clausing went to all that trouble.
Have you seen a true Clausing one to be sure that this was the
case? I don't think that Clausing made the toolposts for their lathes
-- they just bought from Armstrong. The parts are all forged, and it
makes more sense to get them from a vendor who is already set up to make
forged tools than to make one yourself for the machine in question.
I have no way to know if what I have is true Clausing. What I have was
machined, not forged, and lacks Armstrong markings. Although the rocker
could have been forged. Or forged then machined. Not having the
rocker, it's hard to say.
It may be a shop-made replacement.
But -- I wouldn't worry about it anyway. My Clausing came to me
without a lantern style toolpost, and I have been happy to keep it like
that. :-)
My reason is that lantern toolpost tooling does come up used around
here, and it's worthwhile to be able to use it, as it often goes begging.
Well ... I have lantern toolpost and holders for the 6x16"
Atlas/Craftsman -- but I also don't *use* that lathe any more. it was
in pretty bad shape when I first got it -- including some hacksaw
notches in the bed, and significant bed wear near the chucks. It also
had two chucks which were obviously made for the 10" or 12" Atlas, and a
threaded bushing to adapt the two of them to the spindle of the 6x18. :-)
This hastened wear on the spindle bearings (bushings, not roller as in
the later ones).
But it did help me for quite a while until I got better
machines. If I were to use it today, I would make a quick-change
toolpost (of some sort) for it -- or try one of the smaller ones sold to
the hobby crowd.
As it is -- the last significant metalwork related to it was
making something *for* it instead of *with* it. A parting tool hung up
and split off half of the T-slot in the compound top slide, so I had to
make a replacement of good tool steel, instead of the original cast
iron. More recently, I spent some time with the surface grinder turning
the milling spirals on the surface into a nicer finish.
Enjoy,
DoN.
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